The present invention concerns, as a novel industrial product, an aqueous composition, in particular in gel form, based on H2O2, acids and AgII, AgIII, VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions. The invention also relates to a preparation process, in particular when said ions are Ag2+, and to the use of this composition in the field of disinfection, hygiene and/or decontamination, on the one hand, and in the field of surface treatment (in particular cleaning, stripping and/or passivation), on the other hand.
The closest prior art consists of patent document WO-A-96/18301. Before the publication of this document, aqueous disinfecting compositions, some containing hydrogen peroxide and a carboxylic acid/carboxylic peracid mixture of the type RCO2H/RCO3H (in which R is essentially CH3 or CH3CH2) (see in particular to this end EP-A-0 370 850, EP-A-0 193 416, EP-B-0 087 343, FR-A-2 321 301 and FR-A-2 321 302), and others containing hydrogen peroxide and Ag+ ions (see in particular to this end U.S. Pat. No. 3,035,698 and GB-A-2 189 394), had already been proposed in the past, said aqueous disinfecting compositions being stabilized in each case with a strong acid (essentially H3PO4).
These prior aqueous disinfecting compositions, namely (i) those of the type H2O2+RCO2H/RCO3H+H3PO4 and (ii) those of the type H2O2+Ag++H3PO4, are insufficient as regards their absence of efficacy on several strains of bacteria and molds, and in particular on the strains of Penicillium verrucosum. 
A more recent and markedly more effective technique (in particular with regard to said strains of Penicillium verrucosum which were resistant to the two abovementioned types of aqueous disinfecting compositions) was described in the abovementioned WO-A-96/18301, which is incorporated herein by way of reference. According to WO-A-96/18301, the recommended technique uses an aqueous disinfecting, hygiene and decontaminating composition, which comprises, in water:
(A) H2O2,
(B) an RCO2H/RCO3H mixture (in which R is CH3 or CH3CH2),
(C) a silver component as a source of Ag+ ions, and
(D) a stabilizer (mainly H3PO4),
Table IX of WO-A-96/18301 demonstrating the synergy of the aqueous composition containing the components A+B+C+D, compared with the aqueous compositions containing the components A+B+D and A+C+D.
It is found that the aqueous solution of A+B+C+D according to WO-A-96/18301 does not act quickly enough with regard to inhibiting or, better still, destroying microorganisms, such as bacteria, molds, viruses and microscopic algae, in particular by making their wall brittle, especially by degrading their biofilm, by perforating their wall or by preventing them from penetrating into the cells of the body or by protecting said cells against their toxins.
Moreover, the procedures described in GB-A-2 189 394 as regards the preparation of the concentrated aqueous silver solution (i.e. component C above) in the presence of H3PO4, on the one hand, and that of the resulting stabilized concentrated aqueous solution of silver and of hydrogen peroxide (i.e. the aqueous solution containing A+C+D), on the other hand, do not lead to the production of Ag2+ ions or to that of Ag3+ ions.
Specifically, GB-A-2 189 394, which recommends a process comprising:
mixing a strong mineral acid (pH less than 1.6) with a silver component (a silver salt or a silver complex), at a temperature of 50-60xc2x0 C., the strong mineral acid/silver component molar ratio being greater than or equal to 1/1;
cooling the resulting mixture to a temperature of 25-30xc2x0 C. and adding a stabilizing organic acid optionally with gelatin; and
incorporating H2O2 into the resulting mixture,
cites (see page 1, lines 46-50) silver (I) compounds which give Ag+ ions in strong acid medium, these compounds are silver (I) salts and a silver (I) complex salt, namely AgNaCl2, on the one hand, and silver (II) and (III) compounds which are soluble only in basic medium, these compounds are silver (II) and (III) oxides which, in strong acid medium, mainly give metallic silver in fine, on the other hand.
More specifically, the silver (I), (II) and (III) oxides give rise, in acid medium, to the following reactions, in which s denotes a solid product:
Ag2O(s)+2H++2exe2x86x922Ag(s)+H2Oxe2x80x83xe2x80x83(1)
2AgO(s)+2H++2exe2x86x92Ag2O(s)+H2Oxe2x80x83xe2x80x83(2)
Ag2O3(s)+2H++2exe2x86x922AgO(s)+H2Oxe2x80x83xe2x80x83(3)
Since the direct placing in contact (i.e. without a strong acid stabilizer) of H2O2 and of a silver component is liable to cause an explosion, a process different from that recommended by GB-A-2 189 394 should be used to obtain the Ag2+ ions that are useful according to the present invention.
For the same reasons, the procedures described in WO-A-96/18301 do not allow the oxidation in acid medium of silver (I) to silver (II) according to the reaction:
Ag+xe2x86x92Ag2++e.
It is known that, according to U.S. Pat. Nos. 5,017,295 and 5,078,902, Ag2+ ions have been presented as being more active as bactericidal agents than Ag+ ions. Now, it is found that the procedures given in these two documents do not promote the production of Ag2+ or Ag2++Ag3+ ions since, with regard to reaction (2) above, the silver (II) oxide gives in acid medium a precipitate of silver (I) oxide. Thus, the reactions outlined in Example 1 of U.S. Pat. No. 5,017,295 and in Examples 1 and 2 of U.S. Pat. No. 5,078,902, namely:
3AgO+2H3PO4xe2x86x92Ag3(PO4)2+3H2O,
AgO+2HNO3xe2x86x92Ag(NO3)2+H2O,
and
AgO+2HClxe2x86x92AgCl2+H2O,
cannot take place. Furthermore, by reproducing the other method for obtaining Ag2+ ions indicated in Example 2 of U.S. Pat. No. 5,078,902, which comprises the dissolution of AgO in alkaline medium, followed by the addition of an oxidizing source [i.e. oxone (Na2O2)] which can give hydrogen peroxide [this addition is carried out in alkaline medium (i.e. under conditions in which H2O2 intervenes as the reducing agent)], the resulting concentration of Ag2+ ions is very low, such that the redox potential of the aqueous solution containing Ag+ and Ag2+ is always less than 650 mV (at 298 K). Thus, according to U.S. Pat. Nos. 5,017,295 and 5,078,902, the beneficial effects as stated for the Ag2+ ions cannot be manifested.
Finally, U.S. Pat. No. 3,702,298 proposes the use of Ag3+ ions as a germicidal means. However, the mixture Ag++Ag2++Ag3+ effectively obtained has a redox potential ranging from 0.15 mV to 0.4 mV, which is markedly lower than that desired according to the present invention which is greater than 1000 mV.
It is also known that molybdenum intervenes in human beings and warm-blooded animals as a coenzyme for the detoxifying enzymes located in the liver, such as xanthine oxidase, aldehyde oxidase and sulfite oxidase. Mo is essential for converting purine bases into uric acid, and it promotes the intestinal absorption of iron and the retention of fluorine in the body.
It is also known from U.S. Pat. No. 4,995,987 that molybdate and tungstate ions have been proposed, as agents for inhibiting the growth of sulfate-reducing bacteria, in combination with antimicrobial agents. Document U.S. Pat. No. 4,995,987 neither describes nor suggests the subject of the present invention.
In the field of treating metal surfaces, in particular to strip and/or passivate them, it is known that the conventional oxidizing means, such as chromic acid, chromates and nitric acid, are considered as being products that are harmful to the environment.
U.S. Pat. No. 4,537,778 moreover discloses an aqueous mouthwash or oral rinse composition which comprises 0.5-5% by weight of H2O2, 3-15% by weight of ethanol, 0.5-2% by weight of a nonionic and water-soluble surfactant of the polyoxyethylenated polyoxypropylene glycol type, 0.3-2% by weight of a nonionic and water-soluble surfactant of the type such as a C10-C18 fatty acid monoester with polyoxyethylenated sorbitol, a sweetener and a fragrance. This composition may be produced in the form of a paste or a gel by means of a thickener or a gelling agent, respectively. The gelling agent proposed is a gum (xanthan gum or guar gum), a carboxylic interpolymer described in U.S. Pat. No. 2,798,053 or a polyol of the PLURONIC(copyright) type comprising 70% to 20% of hydrophobic groups and 30% to 80% of hydrophilic groups, the preferred gelling agent being PLURONIC(copyright) 127 (see column 4, lines 28-29, column 5, lines 34 and 49, and column 6, lines 5-6). Now, it is found that such a gelling agent, which is of the organic polymer type, is degraded more or less quickly (within the space of a few minutes to a few days) by oxidizing compositions of high redox potential (in particular a redox potential of greater than or equal to 800 mV).
Finally, DE-A-2 659 462 discloses a pharmaceutical composition containing a specific silica gel, namely a silicic acid hydrogel which is usually used in the pharmaceutical field but has never been used under highly oxidizing conditions.
Finally, the prior art neither describes nor suggests the effective use of ions containing a metal with a degree of oxidation close to (in the particular case of AgII) or equal to (in the case of AgIII, VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII) its maximum value, in a disinfecting composition or a composition for treating surfaces.
It is desired, on the one hand, to overcome the abovementioned drawbacks of the prior art, and, on the other hand, to provide a novel technical solution which is effective and unexpected when compared with the teaching of the prior art.
According to a first aspect of the invention, it is proposed to provide a novel technical solution to the problem of disinfection and/or of treating surfaces, which is more effective as regards the speed of action than the technical solution recommended by WO-A-96/18301.
According to a second aspect, it is proposed to provide a novel technical solution which has long-lasting action in order to obtain a persistence of the activity over a longer period of time, in particular when the surface to be treated is inclined or vertical.
The novel technical solution according to the invention for achieving the aforementioned aim is based on the use of specific metal ions, namely AgII, AgIII, VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions.
Thus, an aqueous oxidizing composition (I) is recommended, which is useful in particular in the field of disinfection, hygiene and decontamination, on the one hand, and in the field of treating a metal surface (in particular for cleaning, stripping and/or passivating it) or a nonmetal surface (in particular a plastic or ceramic surface, especially for cleaning and/or stripping it), on the other hand, said composition, which contains, in water, hydrogen peroxide, an RCO2H/RCO3H mixture (in which R is a C1-C6 aliphatic residue containing a linear or branched, saturated or unsaturated hydrocarbon chain) and a stabilizer which is a strong acid and, where appropriate, Ag+ ions, being characterized in that it contains ions of at least one metal M which are AgII, AgIII, VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions, the source L, which gives AgII ions or AgII+AgIII ions, being such that, starting with 100 g of silver (i.e. 157 g of AgNO3) and 1 liter of demineralized water, the concentration of Ag++Ag2+ or Ag++Ag2++Ag3+ ions in the resulting solution gives a redox potential of greater than 1000 mV.
More specifically, the composition (I) according to the invention is characterized in that it contains, in water:
(A) H2O2;
(B) an RCO2H/RCO3H mixture (in which R is a C1-C6 aliphatic residue containing a linear or branched, saturated or unsaturated hydrocarbon-based chain;
(C) metal ions from a source L and chosen from the set consisting of:
(1) ions of a metal M which are AgII, AgIII, VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions,
(2) combinations of Ag+ ions and of ions of said metal M, and
(3) mixtures thereof;
the source L, which gives AgII ions or AgII+AgIII ions, being such that, starting with 100 g of silver (i.e. 157 g of AgNO3) and 1 liter of demineralized water, the concentration of Ag++Ag2+ or Ag++Ag2++Ag3+ ions in the resulting solution gives a redox potential of greater than 1000 mV; and
(D) a stabilizer which is an acid.
This composition may be prepared according to a method which is known per se. The process which is recommended herein comprises the steps consisting in:
(a) using an aqueous solution of a source L giving metal ions chosen from the set consisting of
(1) ions of a metal M which are AgII, AgIII, VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions,
(2) combinations of Ag+ ions and of ions of said metal M, and
(3) mixtures thereof;
the source L, which gives AgII ions or AgII+AgIII ions, being such that, starting with 100 g of silver (i.e. 157 g of AgNO3) and 1 liter of demineralized water, the concentration of Ag++Ag2+ or Ag++Ag2++Ag3+ ions in the resulting solution gives a redox potential of greater than 1000 mV;
(b) introducing the stabilizer into said solution;
(c) introducing said resulting solution thus obtained into aqueous hydrogen peroxide solution or introducing the aqueous hydrogen peroxide solution into said resulting solution;
(d) introducing into the resulting solution thus obtained an acidic substance which is RCO3H, RCO2H or a mixture thereof RCO3H+RCO2H in which R is defined as indicated above;
(e) leaving the resulting solution thus obtained to stand until the equilibrium H2O2+RCO2HH2O+RCO3H is established; and
(f) making up to 100% by weight with water.
The process for preparing a composition according to the invention which contains Ag2+ ions and, where appropriate, Ag3+ ions is characterized in that it comprises the steps consisting in:
(1xc2x0) preparing an aqueous solution of a silver component, which acts as a source of Ag+ ions;
(2xc2x0) oxidizing at least some of the Ag+ ions to Ag2+ ions using persulfate, preferably with sodium persulfate Na2S2O8 or ammonium persulfate (NH4)2S2O8, so as to obtain a redox potential of greater than or equal to 1000 mV, starting with 1 liter of demineralized water and 157 g of AgNO3, and filtering to remove any insoluble material which may be present;
(3xc2x0) introducing the stabilizer into the resulting solution thus obtained;
(4xc2x0) introducing said resulting solution thus obtained into aqueous hydrogen peroxide solution or introducing the aqueous hydrogen peroxide solution into said resulting solution;
(5xc2x0) introducing into the resulting solution thus obtained an acidic substance which is RCO3H, RCO2H or a mixture thereof RCO3H+RCO2H in which R is defined as indicated above;
(6xc2x0) leaving the resulting solution thus obtained to stand until the equilibrium H2O2+RCO2HH2O+RCO3H is established; and
(7xc2x0) making up to 100% by weight with water.
When carrying out this process, Ag3+ ions are liable to be obtained at least in trace amount.
According to the invention, a gelled composition (II) is also recommended, which is characterized in that it comprises:
the aqueous composition (I) mentioned above, and
a gelling agent.
In practice, the gelled composition (II) will comprise 50% to 99.7% by weight of said aqueous composition (I) and 50% to 0.3% by weight of gelling agent. More specifically, the preferred gelling agent will be a pyrogenic colloidal silica or a compound of the polyacrylic type such as CARBOPOL(copyright) ETD 2623 from the company Goodrich, which is a copolymer of a C10-C30 alkyl acrylate, or CARBOPOL(copyright) 672 also from the company Goodrich, which is a polyacrylic homopolymer.
The process for preparing the gelled composition (II) consists (i) in placing said composition (I) in contact with the gelling agent, (ii) in stirring the resulting mixture for 3 to 20 minutes, and (iii) in leaving the resulting mixture to stand in order for it to set to a gel.
In the text hereinbelow, except where otherwise mentioned, the respective amounts of the ingredients of the aqueous decontaminating composition according to the invention are expressed as percentages by weight, and the dilutions of said composition are expressed according to the ratio of the initial volume to the volume of the resulting dilute composition.
Hydrogen Peroxide
In general, the aqueous composition (I) according to the invention contains an H2O2 content which is less than or equal to 60% by weight relative to the weight of said composition. Thus, the composition (I) according to the invention may contain 0.1% to 60% by weight of H2O2 and may be diluted at the time of use (when the H2O2 concentration is greater than or equal to 4% by weight in particular.
In practice, since hydrogen peroxide raises transportation difficulties, when an aqueous hydrogen peroxide solution with an H2O2 content of greater than 8% by weight is used, especially with regard to the French and EC regulations, it would be advisable to provide an aqueous composition (I) containing not more than 8% by weight and better still not more than 7.9% by weight of H2O2.
Consequently, the aqueous composition (I) according to the invention will advantageously comprise an H2O2 content of about 7.5-7.9% by weight and will be diluted, at the time of use, with water in particular to a final H2O2 concentration of less than or equal to 4% by weight.
RCO2H/RCO3H Mixture
With regard to the equilibrium reaction (4):
H2O2+RCO2HH2O+RCO3Hxe2x80x83xe2x80x83(4)
the respective amounts of RCO3H and RCO2H in the mixture RCO3H/RCO2H are not critical. It suffices to have in contact in H2O either H2O2 and RCO3H or H2O2 and RCO2H in order to obtain a ternary mixture H2O2+RCO3H+RCO2H provided that H2O2 is in excess relative to the RCO2H/RCO3H pair. Thus it suffices, as it were, to incorporate:
(i) RCO2H in the presence of H2O2, or
(ii) RCO3H (which in concentrated form generally contains H2O2 and RCO2H according to documents FR-A-2 321 301 and FR-A-2 321 302 mentioned above),
in H2O, in order to obtain at equilibrium the combination H2O2+RCO3H+RCO2H.
As mentioned above, the group R of the acid/peracid pair represents a C1-C6 aliphatic residue containing a linear or branched, saturated or unsaturated hydrocarbon chain. Advantageously, use will be made of a group R containing a saturated linear hydrocarbon chain such as CH3; CH3CH2 or CH3(CH2)4 or alternatively of a group R containing an unsaturated linear hydrocarbon chain such as, in particular, CH3xe2x80x94CHxe2x95x90CH, CH3xe2x80x94CHxe2x95x90CHxe2x80x94CH2 or CH3xe2x80x94CHxe2x95x90CHxe2x80x94CHxe2x95x90CH.
The preferred groups R are (in order of increasing preference): CH3xe2x80x94CHxe2x95x90CHxe2x80x94CHxe2x95x90CH, CH3CH2 or CH3. In general, the pair
CH3CO2H/CH3CO3H (i.e. R=methyl)
is preferred to the pair
CH3CH2CO2H/CH3CH2CO3H (i.e. R=ethyl)
since the first pair is more active than the second pair as a disinfecting/decontaminating means in the aqueous composition according to the invention.
Advantageously, in the aqueous composition (I) according to the invention, the weight ratio B/A of the mixture RCO2H/RCO3H to the hydrogen peroxide will be between 0.15/1 and 0.85/1. Preferably, this weight ratio will be between 0.5/1 and 0.7/1.
The Source L
The source L serves to provide the ions that are useful according to the invention, namely the ions containing the metal M (i.e. AgII, AgIII, VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions), the combination Ag+/ions of the metal M, or mixtures thereof.
When VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions are desired, use will be made of a source L which is a salt in which said metal M is in its maximum oxidation state. As a variant, a source L which may be used is an oxide of said metal M (in this case an oxide of VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII) if said oxide is soluble in acids.
When Ag2+ ions are desired, the oxidation of Ag+ (advantageously obtained from AgNO3 or from colloidal silver) to Ag2+ should be carried out.
The procedures recommended for the reaction Ag+xe2x86x92Ag2++e are given later. Since this reaction is generally incomplete, it mainly gives a mixture of Ag+/Ag2+ ions [and, where appropriate, a mixture of Ag+/Ag2+/Ag3+ ions in which the Ag3+ ions are at least in trace amount].
When Ag+ ions are desired in combination with VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions, the ions obtained from the corresponding two sources are mixed together.
Finally, when an ionic mixture Ag+/Ag2+/VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions is desired, the Ag+/Ag2+ ions obtained from their source by oxidation as indicated above are mixed with the ions from the abovementioned source of VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions.
The preferred ions according to the invention comprise the VV, MoVI, WVI, and TlIII ions, on the one hand, and the ion mixtures Ag+/Ag2+, Ag+/MoVI, Ag+/WVI, Ag+/TlIII and Ag+/Ag2+/MoVI, on the other hand, the most advantageous ions being Ag+/Ag2+, Ag+/MoVI, Ag+/Ag2+/MoVI and above all the MoVI ions.
It has been found, unexpectedly, during the use of the aqueous composition (I) according to the invention, that molybdenum has a twofold advantage over silver (in the form Ag+ or Ag+/Ag2+):
as regards microorganisms, it is more active than silver, and
during the cold sterilization of instruments (in particular dental or surgical instruments), it does not give the unattractive gray or black deposits of silver.
The main source of VV ions is a VO2+ (or, where appropriate, VO3xe2x88x92) salt, that of NbV ions is an NbO3+ salt, that of MoVI ions is an MoO32+ or MoO42xe2x88x92 salt, that of CoIII ions is a Co3+ salt, that of WVI ions is a WO42xe2x88x92 salt, that of TaV ions is a Ta5+ salt, that of InIII ions is an In3+ salt, and that of TlIII ions is a Tl3+ salt.
The ions of the component C according to the invention act on microorganisms by making their wall brittle or by degrading it, on the one hand, and they also act as oxidizing means, in particular according to the following reactions, on the other hand.
VO2++2H++exe2x86x92VO2++H2O or, where appropriate,xe2x80x83xe2x80x83(5)
VO3xe2x88x92+4H++exe2x86x92VO2++2H2Oxe2x80x83xe2x80x83(5a)
NbV+e2exe2x86x92NbIII orxe2x80x83xe2x80x83(6)
NbO3++2H++e2exe2x86x92Nb3++H2Oxe2x80x83xe2x80x83(6a)
MoO22++2H++exe2x86x92MoO3++H2Oxe2x80x83xe2x80x83or (7)
MoO42xe2x88x92+4H++exe2x86x92MoO2++2H2Oxe2x80x83xe2x80x83(7a)
Co3++exe2x86x92Co2+(in acidic medium)xe2x80x83xe2x80x83(8)
In3xe2x88x92+2exe2x86x92In+xe2x80x83xe2x80x83(9)
Tl3++2exe2x86x92Tl+.xe2x80x83xe2x80x83(10)
In practice, it is recommended as regards efficacy for the source L to be able to give, starting with an amount corresponding to 100 g of metal M and 1 liter of demineralized water, a resulting solution containing AgII, AgIII, VV, NbV, TaV, MoVI, WVI, CoIIIInIII and/or TlIII ions with a redox potential of greater than 1 V.
Advantageously, the weight ratio of the source L of ions to the hydrogen peroxide will be between 0.0005/1 and 0.015/1. In practice, this weight ratio will be even more advantageously between 0.0008/1 and 0.005/1 and better still about 0.001/1.
The Stabilizer
The stabilizer, which protects H2O2 and the ions from the source L and which avoids any risk of explosion, in particular using concentrated solutions of (i) H2O2 and (ii) Ag+ and/or Ag2+, is chosen from the combination consisting of mineral acids such as H3PO4 and H2SO4 (nitric acid and hydrochloric acid being strongly advised against, in particular on account of their harmful effects on metal surfaces and/or the environment), on the one hand, and organic acids such as pyridinecarboxylic acids, on the other hand. The preferred stabilizer according to the invention is H3PO4 or (especially when the source L provides MoVI ions) a pyridinecarboxylic acid.
Pyridinecarboxylic acids are substances of formula: 
namely, 2-pyridinecarboxylic acid (picolinic acid), 3-pyridinecarboxylic acid (nicotinic acid) and 4-pyridinecarboxylic acid (isonicotinic acid).
When the source L of ions gives Ag+ or Ag+/Ag2+ ions, it is advantageous to add, where appropriate, a small amount of gelatin to the acidic stabilizer of the component D.
Advantageously, the weight ratio of the stabilizer to the hydrogen peroxide will be between 0.0005/1 and 0.025/1. In practice, this weight ratio will be even more advantageously between 0.0008/1 and 0.005/1 and better still about 0.001/1.
The Other Additives
At least one of the following components may also be incorporated into the aqueous composition (I) according to the invention:
(E) wetting agent;
(F) anticorrosion agent; and
(G) fragrance.
The wetting agent which is included herein is (i) an amphiphilic, amphoteric, anionic or nonionic surfactant compound, such as polyols that are suitable in particular for contact with foodstuffs and, where appropriate, suitable for oral administration with drinking water at the dose considered for use, or (ii) a mixture of such compounds. The product sold under the name Tegol(copyright) 2000 is suitable for this purpose as an amphoteric wetting agent.
In the aqueous composition (I) according to the invention, the weight ratio of the wetting agent to the hydrogen peroxide will advantageously be between 0.00005/1 and 0.01/1. In practice, this weight ratio will be even more advantageously about 0.005/1.
It is recommended to incorporate into the aqueous composition (I) according to the invention an anticorrosion agent which, at the dose used, is suitable for contact with foodstuffs and/or oral administration with drinking water. As anticorrosion agents which may be used for this purpose, mention may be made in particular of aminophosphonic acids as described in the abovementioned FR-A-2 321 302, the sodium, potassium, ammonium and alkanolamine salts thereof, and mixtures thereof. Hydroxyethanediphosphonic acid, dimethylaminomethanediphosphonic acid and ethylenediaminotetrakis(methylenephosphonic acid), the Na, K, NH4+ or alkanolamine salts thereof, and mixtures thereof, are particularly suitable for the aqueous composition (I) according to the invention. 1,2,3-Benzotriazole is also suitable as an anticorrosion agent.
In practice, the anticorrosion agent will be present in the aqueous composition (I) at low concentration. If it is used, said anticorrosion agent will be included especially in an amount such that the weight ratio of said anticorrosion agent to the hydrogen peroxide is between 0.00005/1 and 0.03/1 and preferably between 0.001/1 and 0.005/1.
As indicated in WO-A-96/18301, it is prudent to limit the corrosion of metal surfaces (mainly made of iron or copper) in very prolonged contact with the aqueous composition (I) of the invention to a value of less than 200 xcexcm/year.
As the corrosion of metal surfaces is mainly reflected by a phenomenon known as xe2x80x9cpittingxe2x80x9d, it is appropriate to avoid the formation of said pitting in which the microorganisms which it is desired to irradicate would live and grow.
The fragrance component in point (G) will be included in the aqueous decontaminating composition in an amount of less than or equal to that of the anticorrosion agent in point (F).
The water which is included in the decontaminating composition according to the invention is advantageously a purified water, namely distilled water, demineralized water or, better still, deionized water. Preferably, the deionized water used herein will be a water with a resistivity of greater than 105 xcexa9/cm and better still greater than or equal to 106 xcexa9/cm.
The water used for any diluting of said decontaminating composition according to the invention will advantageously be purified water as indicated above.
The pH of the aqueous composition according to the invention is (before dilution and then use) generally between 1.2 and 5 and better still between 1.5 and 4. It is adjusted by means of the preferred component D: H3PO4 or pyridinecarboxylic acid.
The Aqueous Composition (I)
Preferably, the aqueous composition (I) according to the invention, with regard to the foregoing text, contains, in water:
(A) not more than 8% by weight of H2O2;
(B) a mixture RCO2H/RCO3H (in which R is CH3 or CH3CH2), in a weight ratio of said mixture RCO2H/RCO3H to hydrogen peroxide of from 0.15/1 to 0.85/1 and preferably from 0.5/1 to 0.7/1;
(C) a source L providing metal ions chosen from the combination consisting of:
(1) ions of a metal M which are AgII, AgIII, VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions,
(2) combinations of Ag+ ions and of ions of said metal M, and
(3) mixtures thereof,
the source L, which gives AgII ions or AgII+AgIII ions, being such that, starting with 100 g of silver (i.e. 157 g of AgNO3) and 1 liter of demineralized water, the concentration of Ag++Ag2+ or Ag++Ag2++Ag3+ ions in the resulting solution gives a redox potential of greater than 1000 mV;
according to a weight ratio of said source L to hydrogen peroxide of from 0.0005/1 to 0.015/1 and preferably from 0.0008/1 to 0.005/1; and
(D) a stabilizer, in a weight ratio of said stabilizer to hydrogen peroxide of from 0.0005/1 to 0.015/1 and preferably from 0.0008/1 to 0.005/1.
Even more practically, a standard composition (i.e. a stock composition) which is intended to be diluted at the time of use is recommended. This standard composition contains:
(A) 7.5-7.9% by weight of H2O2;
(B) 4.5% to 4.8% by weight of a mixture CH3CO3H+CH3CO2H;
(C) 0.005% to 0.01% by weight of the source L;
(D) 0.0005% to 0.01% by weight of H3PO4 or of pyridinecarboxylic acid;
(E) where appropriate, 0.0075% to 0.04% by weight of surfactant;
(F) where appropriate, 0.003% to 0.04% by weight of anticorrosion agent;
(G) where appropriate, a fragrance; and
water (distilled, demineralized or deionized) to make up to 100% by weight.
It may be advantageous, in particular in the context of the cleaning, stripping and/or passivation treatment of a metal surface or in the context of the cleaning and/or stripping treatment of a nonmetal surface, for the weight ratio C/D to be less than 1/1.
Moreover, when the component C is a mixture of Ag+ ions and of M ions, it suffices, according to the invention, for the metal ions of M to be in trace amount in order for the beneficial effects to be manifested.
Preparation of the Composition (I)
The process for preparing the aqueous composition (I) according to the invention, which is given above and comprises steps (a)-(f), is carried out directly when the source L contains no Ag2+ (or Ag2+/Ag3+) ions. In this case, said composition may be produced according to the teaching of GB-A-2 189 394 (in order to obtain a high concentration of H2O2), on the one hand, and then by diluting (for an H2O2 concentration of less than or equal to 8% by weight and better still less than or equal to 7.9% by weight) with distilled, demineralized or deionized water for the purpose of transportation, on the other hand. As a variant, said composition may be produced directly in the form of a standard composition.
When the source L gives Ag2+ (or Ag2+/Ag3+) ions, step (a) is then replaced with steps (1xc2x0) and (2xc2x0) to make use of a source of Ag+ ions, which are oxidized to Ag2+ ions. This oxidation is carried out (i) using a persulfate, preferably sodium persulfate or ammonium persulfate, as oxidizing agent, and (ii) in the absence of white light to avoid the UV-mediated reduction of the silver ions to metallic silver which precipitates in situ. The oxidation Ag+xe2x86x92Ag2++e will advantageously be performed in darkness (i.e. in opaque reactors) or in red light.
The filtration included at the end of step (2xc2x0) has the purpose of removing any insoluble material which may be present in the reaction medium. The presence of an insoluble material is mainly manifested when the persulfate used is ammonium persulfate. Advantageously, this filtration is carried out using a filter membrane having pores with a diameter of about 3 xcexcm.
In step (3xc2x0)xe2x80x94i.e. step (b) of the general processxe2x80x94the silver ions obtained (generally a mixture of Ag+, Ag2+ and, where appropriate, Ag3+) are preferably stabilized using H3PO4 (as an aqueous solution at 70-85% by weight) or using a pyridinecarboxylic acid.
Even more advantageously, a small amount of gelatin will be added before, during or after the addition of H3PO4 or of a pyridinecarboxylic acid.
As indicated above, if it contains Ag2+ or Ag2++Ag3+ ions, the aqueous composition according to the invention may be produced either in the form of a standard solution or in the form of a solution with a high H2O2 content before dilution for transportation.
One of the preferred modes (mode A) for carrying out the process for preparing the composition (I) according to the invention, when the source L gives VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII ions, comprises the following steps (for the production of a standard composition containing 7.5-7.9% by weight of H2O2) consisting in:
(a) preparing a solution of a VV, NbV, TaV, MoVI, WVI, CoIII, InIII or TlIII salt (advantageously in acidic medium) in a portion of the total amount of water required to prepare said aqueous disinfecting composition;
(b) introducing into the resulting solution thus obtained an aqueous phosphoric acid solution containing 70% to 85% by weight of H3PO4 or an aqueous pyridinecarboxylic acid solution;
(c) introducing the resulting solution thus obtained into an aqueous hydrogen peroxide solution containing 50% to 60% by weight of H2O2, with stirring, at a temperature of between 0xc2x0 C. and 25xc2x0 C. (preferably at a temperature of between 4xc2x0 C. and 15xc2x0 C.), and with a rate of introduction of the solution obtained in step (b) of between 3 and 6 l/h;
(d) introducing into the resulting solution thus obtained the acidic substance CH3CO2H, with stirring, at a temperature of between 0xc2x0 C. and 25xc2x0 C. (preferably at a temperature of between 4xc2x0 C. and 15xc2x0 C.) and with a rate of introduction of the acidic substance CH3CO2H of between 3 and 6 l/h;
(e) leaving the resulting solution thus obtained to stand for 48 hours (preferably in darkness), at a temperature of between 0xc2x0 C. and 25xc2x0 C. (preferably at a temperature of between 4xc2x0 C. and 15xc2x0 C.), in order for the equilibrium
H2O2+CH3CO2HCH3CO3H+H2O
xe2x80x83to be established, and
(f) adding the remaining water to make up to 100% by weight.
In step (d) of the preparation of this composition, the acid CH3CO2H may be introduced in the form of an aqueous solution.
Another preferred mode (mode B) for carrying out the process for preparing the composition (I) according to the invention, when the source L provides Ag2+ ions (with, where appropriate, Ag3+ ions) comprises the following steps (for the production of a standard composition containing 7.5-7.9% by weight of H2O2) consisting in:
(1xc2x0) dissolving AgNO3 in demineralized water with a resistivity of 106 xcexa9/cm (in a proportion of 157 g of silver nitratexe2x80x94i.e. 100 g of silverxe2x80x94to 1 liter of demineralized water), the redox potential of the solution thus obtained being about 600 mV;
(2xc2x0) oxidizing at least a portion of the Ag+ ions of the above solution to Ag2+ or to Ag2++Ag3+ by addition of sodium persulfate or ammonium persulfate, so as to obtain a redox potential of greater than or equal to 1000 mV (in particular a redox potential of greater than or equal to 1600 mV); filtering (on a membrane with pores 3 xcexcm in diameter);
(3xc2x0) stabilizing the resulting solution thus obtained using an aqueous phosphoric acid solution containing 70% to 85% by weight of H3PO4 [in a proportion of from 10 to 100 ml of aqueous H3PO4 solution at 70% to 85% by weight per 1 liter of demineralized water used in step (1xc2x0)] or using an aqueous pyridinecarboxylic acid solution [after stirring for 24 hours at room temperature, the solution of silver ions thus stabilized having a redox potential of greater than or equal to 1000 mV];
(4xc2x0) introducing the resulting solution thus obtained into an aqueous hydrogen peroxide solution containing 50% to 60% by weight of H2O2, with stirring, at a temperature of between 0xc2x0 C. and 25xc2x0 C. (preferably at a temperature of between 4xc2x0 C. and 15xc2x0 C.), and with a rate of introduction of the solution obtained in step (3xc2x0) of between 3 and 6 l/h;
(5xc2x0) introducing into the resulting solution thus obtained the acidic substance CH3CO2H, with stirring, at a temperature of between 0xc2x0 C. and 25xc2x0 C. (preferably at a temperature of between 4xc2x0 C. and 15xc2x0 C.), and with a rate of introduction of the acidic substance CH3CO2H of between 3 and 6 l/h;
(6xc2x0) leaving the resulting solution thus obtained to stand for 48 hours, in darkness (or in red light) at a temperature of between 0xc2x0 C. and 25xc2x0 C. (preferably at a temperature of between 4xc2x0 C. and 15xc2x0 C.), in order for the equilibrium
H2O2+CH3CO2HCH3CO3H+H2O
xe2x80x83to be established, and
(7xc2x0) adding water to make up to 100% by weight.
In step (5xc2x0) of the preparation of this standard composition, the acid CH3CO2H may be introduced in the form of an aqueous solution.
The Gelled Composition (II)
The gelled composition (II) in accordance with the invention is obtained using the aqueous composition (I) and a specific gelling agent, which is a mineral substance or an organic substance. When this gelling agent is a mineral substance, it is advantageously pyrogenic colloidal silica which is, in dry form, in the form of particles with an area per unit mass of from 80 to 400 m2/g and a mean particle size of from 7 to 20 nm. Among the silicas which are suitable for this purpose, mention may be made in particular of those sold by the company Cabot under the name CAB-O-SIL(copyright), and in particular the products CAB-O-SIL(copyright) LM-150, CAB-O-SIL(copyright) M-5, CAB-O-SIL(copyright) EH-5 and CAB-O-SIL(copyright) M-7D, which are hydrophilic.
In order to produce a gelled composition (100 parts by weight) containing pyrogenic silica, the process is performed as follows:
placing composition (I) (50 to 99 parts by weight) and the pyrogenic colloidal silica (50 to 1 parts by weight) in contact,
stirring for 3-10 minutes with an angular speed of the stirrer of from 1500 to 2000 rpm, and then
leaving to stand at room temperature.
When the gelling agent is an organic substance, it is advantageously a polyacrylic material as indicated above. In this case, the gelled composition (100 parts by weight) which contains said polyacrylic material will be prepared as follows:
placing the composition (I) (90 to 99.7 parts by weight) and the organic gelling material (10 to 0.3 parts by weight) in contact,
stirring for 10-20 minutes with an angular speed of the stirrer of from 1000 to 2000 rpm, and then
leaving to stand at room temperature.
The gelled composition (II) containing a polyacrylic organic gelling material can be used only at a pH of greater than or equal to 3.5; in practice, it will be used at a pH of from 3.5 to 7 and preferably at pH 5. Moreover, it is suitable for the preparation of transparent gels that are valued by the public in dermatology and in cosmetology.
On the other hand, the gelled composition (II) containing pyrogenic silica will advantageously be used at a pH of from 1.5 to 4.
The gel obtained has thixotropic properties: it becomes fluid under a stress such as stirring, friction or shear and sets to a solid quickly (in less than 5 minutes) when the stirring, friction or shear stops.
Moreover, this gel is stable in acidic or weakly alkaline medium; it is also stable up to the degradation temperature of its constituents.
Depending on the water content, said gel may be prepared in a wide range of viscosities.
On account of its thixotropic properties, the gelled composition (II) according to the invention is particularly suitable for decontaminating aged oils and greases (which are the nutrient media of several microorganisms liable to be pathogenic) in situ in industrial plants and devices.
The Uses
The uses of the aqueous oxidizing composition (I) according to the invention comprise (i) those envisaged in the abovementioned publication WO-A-96/18301 (see page 20, line 11 to page 22, line 15) in particular as regards the disinfection of water to make it fit for drinking, the hygiene of industrial premises and swimming pools, the cold sterilization of surgical and dental instruments, the protection of plants and crops against bacteria, molds, viruses and parasites, the protection of fish, crustaceans and shellfish against pathogenic algae such as Euglena, and the decontamination of mining sites, and (ii) the novel uses which relate to the cleaning, stripping and/or passivation of metal surfaces (in particular surfaces made of steel or aluminum) or nonmetal surfaces (in particular plastic or ceramic surfaces, the plastic surfaces comprising herein those of floor-covering or wall panels which are exposed and which are generally made of PVC, polyacrylate, polycarbonate or the like).
Advantageously, the composition (I) intended for disinfection and hygiene will be obtained by diluting a standard composition so as to have an H2O2 concentration of from 1% to 2% by weight.
Also advantageously, the composition (I) intended for decontaminating mining sites will have an H2O2 content of from 4% to 7.9% by weight and will be diluted at the time of use to a final working concentration of less than or equal to 1/100 (i.e. a final H2O2 content of less than or equal to 0.04% by weight).
In the field of treating surfaces, the composition (I) will advantageously have an H2O2 content of between 1% and 7.9% by weight and will comprise a weight ratio C/D of less than 1/1 and greater than 1/2.
The gelled composition (II) according to the invention offers the advantage of providing, in the region of the article or surface to be treated, a source of H2O2 and of ions originating from L which is stabilized and which ensures long-lasting action.
The gelled composition (II) is particularly useful with regard to surfaces that are not horizontal, i.e. vertical, curved or inclined surfaces. It is most particularly suitable for protecting constructions against microorganisms liable to grow in the cavities of the outer walls of buildings exposed to dust and to bird droppings, on the one hand, and for stripping and passivating metal reactors or tanks, on the other hand.
The gelled composition II is thus recommended according to the invention for use, on the one hand, as a germicidal product for p reparing a medicinal product intended for therapeutic use with regard to oral conditions, in particular of the periodontium, caused by bacteria and/or fungi, and, on the other hand, as a cosmetic product, in p articular in the form of a toothpaste, for oral hygiene.
In the dental field, it has been found that the gelled composition (II) serves as a hemostatic agent, dispenses with the administration of antibacterial and/or antifungal agents, inhibits catalase and ensures the passivation of the metal surfaces of bridges (said passivation preventing the deposition of bacteria and fungi over a long period of time), and also the temporary protection of plastic or ceramic surfaces against said bacteria and fungi (their deposition thus being prevented). This gelled composition is suitable for preparing toothpastes containing 1% to 2% by weight of hydrogen peroxide.